/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  AES implementation in JavaScript (c) Chris Veness 2005-2012                                   */
/*   - see http://csrc.nist.gov/publications/PubsFIPS.html#197                                    */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

var Aes = {}; // Aes namespace

/**
 * AES Cipher function: encrypt 'input' state with Rijndael algorithm
 *   applies Nr rounds (10/12/14) using key schedule w for 'add round key' stage
 *
 * @param {Number[]} input 16-byte (128-bit) input state array
 * @param {Number[][]} w   Key schedule as 2D byte-array (Nr+1 x Nb bytes)
 * @returns {Number[]}     Encrypted output state array
 */
Aes.cipher = function(input, w) { // main Cipher function [§5.1]
    var Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
    var Nr = w.length / Nb - 1; // no of rounds: 10/12/14 for 128/192/256-bit keys

    var state = [
        [],
        [],
        [],
        []
    ]; // initialise 4xNb byte-array 'state' with input [§3.4]
    for (var i = 0; i < 4 * Nb; i++) state[i % 4][Math.floor(i / 4)] = input[i];

    state = Aes.addRoundKey(state, w, 0, Nb);

    for (var round = 1; round < Nr; round++) {
        state = Aes.subBytes(state, Nb);
        state = Aes.shiftRows(state, Nb);
        state = Aes.mixColumns(state, Nb);
        state = Aes.addRoundKey(state, w, round, Nb);
    }

    state = Aes.subBytes(state, Nb);
    state = Aes.shiftRows(state, Nb);
    state = Aes.addRoundKey(state, w, Nr, Nb);

    var output = new Array(4 * Nb); // convert state to 1-d array before returning [§3.4]
    for (var i = 0; i < 4 * Nb; i++) output[i] = state[i % 4][Math.floor(i / 4)];
    return output;
}

/**
 * Perform Key Expansion to generate a Key Schedule
 *
 * @param {Number[]} key Key as 16/24/32-byte array
 * @returns {Number[][]} Expanded key schedule as 2D byte-array (Nr+1 x Nb bytes)
 */
Aes.keyExpansion = function(key) { // generate Key Schedule (byte-array Nr+1 x Nb) from Key [§5.2]
    var Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
    var Nk = key.length / 4 // key length (in words): 4/6/8 for 128/192/256-bit keys
    var Nr = Nk + 6; // no of rounds: 10/12/14 for 128/192/256-bit keys

    var w = new Array(Nb * (Nr + 1));
    var temp = new Array(4);

    for (var i = 0; i < Nk; i++) {
        var r = [key[4 * i], key[4 * i + 1], key[4 * i + 2], key[4 * i + 3]];
        w[i] = r;
    }

    for (var i = Nk; i < (Nb * (Nr + 1)); i++) {
        w[i] = new Array(4);
        for (var t = 0; t < 4; t++) temp[t] = w[i - 1][t];
        if (i % Nk == 0) {
            temp = Aes.subWord(Aes.rotWord(temp));
            for (var t = 0; t < 4; t++) temp[t] ^= Aes.rCon[i / Nk][t];
        } else if (Nk > 6 && i % Nk == 4) {
            temp = Aes.subWord(temp);
        }
        for (var t = 0; t < 4; t++) w[i][t] = w[i - Nk][t] ^ temp[t];
    }

    return w;
}

/*
 * ---- remaining routines are private, not called externally ----
 */

Aes.subBytes = function(s, Nb) { // apply SBox to state S [§5.1.1]
    for (var r = 0; r < 4; r++) {
        for (var c = 0; c < Nb; c++) s[r][c] = Aes.sBox[s[r][c]];
    }
    return s;
}

Aes.shiftRows = function(s, Nb) { // shift row r of state S left by r bytes [§5.1.2]
    var t = new Array(4);
    for (var r = 1; r < 4; r++) {
        for (var c = 0; c < 4; c++) t[c] = s[r][(c + r) % Nb]; // shift into temp copy
        for (var c = 0; c < 4; c++) s[r][c] = t[c]; // and copy back
    } // note that this will work for Nb=4,5,6, but not 7,8 (always 4 for AES):
    return s; // see asmaes.sourceforge.net/rijndael/rijndaelImplementation.pdf
}

Aes.mixColumns = function(s, Nb) { // combine bytes of each col of state S [§5.1.3]
    for (var c = 0; c < 4; c++) {
        var a = new Array(4); // 'a' is a copy of the current column from 's'
        var b = new Array(4); // 'b' is a•{02} in GF(2^8)
        for (var i = 0; i < 4; i++) {
            a[i] = s[i][c];
            b[i] = s[i][c] & 0x80 ? s[i][c] << 1 ^ 0x011b : s[i][c] << 1;

        }
        // a[n] ^ b[n] is a•{03} in GF(2^8)
        s[0][c] = b[0] ^ a[1] ^ b[1] ^ a[2] ^ a[3]; // 2*a0 + 3*a1 + a2 + a3
        s[1][c] = a[0] ^ b[1] ^ a[2] ^ b[2] ^ a[3]; // a0 * 2*a1 + 3*a2 + a3
        s[2][c] = a[0] ^ a[1] ^ b[2] ^ a[3] ^ b[3]; // a0 + a1 + 2*a2 + 3*a3
        s[3][c] = a[0] ^ b[0] ^ a[1] ^ a[2] ^ b[3]; // 3*a0 + a1 + a2 + 2*a3
    }
    return s;
}

Aes.addRoundKey = function(state, w, rnd, Nb) { // xor Round Key into state S [§5.1.4]
    for (var r = 0; r < 4; r++) {
        for (var c = 0; c < Nb; c++) state[r][c] ^= w[rnd * 4 + c][r];
    }
    return state;
}

Aes.subWord = function(w) { // apply SBox to 4-byte word w
    for (var i = 0; i < 4; i++) w[i] = Aes.sBox[w[i]];
    return w;
}

Aes.rotWord = function(w) { // rotate 4-byte word w left by one byte
    var tmp = w[0];
    for (var i = 0; i < 3; i++) w[i] = w[i + 1];
    w[3] = tmp;
    return w;
}

// sBox is pre-computed multiplicative inverse in GF(2^8) used in subBytes and keyExpansion [§5.1.1]
Aes.sBox = [0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
    0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
    0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
    0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
    0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
    0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
    0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
    0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
    0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
];

// rCon is Round Constant used for the Key Expansion [1st col is 2^(r-1) in GF(2^8)] [§5.2]
Aes.rCon = [
    [0x00, 0x00, 0x00, 0x00],
    [0x01, 0x00, 0x00, 0x00],
    [0x02, 0x00, 0x00, 0x00],
    [0x04, 0x00, 0x00, 0x00],
    [0x08, 0x00, 0x00, 0x00],
    [0x10, 0x00, 0x00, 0x00],
    [0x20, 0x00, 0x00, 0x00],
    [0x40, 0x00, 0x00, 0x00],
    [0x80, 0x00, 0x00, 0x00],
    [0x1b, 0x00, 0x00, 0x00],
    [0x36, 0x00, 0x00, 0x00]
];


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  AES Counter-mode implementation in JavaScript (c) Chris Veness 2005-2012                      */
/*   - see http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf                       */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

Aes.Ctr = {}; // Aes.Ctr namespace: a subclass or extension of Aes


Aes.Ctr.getKeySchedule = function(password, nBits) {
    var st = typeof(password) == "string"
    password = st ? Utf8.encode(password) : password;
    var charCodeAt = st ? function(id) { return password.charCodeAt(id) } : function(id) { return password[id] }

    var nBytes = nBits / 8; // no bytes in key (16/24/32)
    var pwBytes = new Array(nBytes);
    for (var i = 0; i < nBytes; i++) { // use 1st 16/24/32 chars of password for key
        pwBytes[i] = isNaN(charCodeAt(i)) ? 0 : charCodeAt(i) || 0;
    }
    var key = Aes.cipher(pwBytes, Aes.keyExpansion(pwBytes)); // gives us 16-byte key
    key = key.concat(key.slice(0, nBytes - 16)); // expand key to 16/24/32 bytes long

    var keySchedule = Aes.keyExpansion(key);
    return keySchedule
}



/** 
 * Encrypt a text using AES encryption in Counter mode of operation
 *
 * Unicode multi-byte character safe
 *
 * @param {String} plaintext Source text to be encrypted
 * @param {String} password  The password to use to generate a key
 * @param {Number} nBits     Number of bits to be used in the key (128, 192, or 256)
 * @returns {string}         Encrypted text
 */
Aes.Ctr.encrypt = function(plaintext, password, nBits, to) {
    var blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
    if (!(nBits == 128 || nBits == 192 || nBits == 256)) return ''; // standard allows 128/192/256 bit keys

    var st = typeof(plaintext) == "string"
    plaintext = st ? Utf8.encode(plaintext) : plaintext;
    //var t = new Date();  // timer

    var charCodeAt = st ? function(id) { return plaintext.charCodeAt(id) } : function(id) { return plaintext[id] }
    var fromCharCode = !to ? function(id) { return String.fromCharCode(id) } : function(id) { return id }

    // use AES itself to encrypt password to get cipher key (using plain password as source for key 
    // expansion) - gives us well encrypted key (though hashed key might be preferred for prod'n use)

    // initialise 1st 8 bytes of counter block with nonce (NIST SP800-38A §B.2): [0-1] = millisec, 
    // [2-3] = random, [4-7] = seconds, together giving full sub-millisec uniqueness up to Feb 2106
    var counterBlock = new Array(blockSize);

    var nonce = (new Date()).getTime(); // timestamp: milliseconds since 1-Jan-1970
    var nonceMs = nonce % 1000;
    var nonceSec = Math.floor(nonce / 1000);
    var nonceRnd = Math.floor(Math.random() * 0xffff);

    for (var i = 0; i < 2; i++) counterBlock[i] = (nonceMs >>> i * 8) & 0xff;
    for (var i = 0; i < 2; i++) counterBlock[i + 2] = (nonceRnd >>> i * 8) & 0xff;
    for (var i = 0; i < 4; i++) counterBlock[i + 4] = (nonceSec >>> i * 8) & 0xff;

    // and convert it to a string to go on the front of the ciphertext

    var pl = plaintext.length || plaintext.byteLength || 0
    var ciphertxt = (!to || to == 1) ? new Array(pl + 8) : new Uint8Array(pl + 8)
        //var ctrTxt = '';
    for (var i = 0, ti = 0; i < 8; i++, ti++) ciphertxt[ti] = fromCharCode(counterBlock[i]);

    // generate key schedule - an expansion of the key into distinct Key Rounds for each round
    var keySchedule = this.getKeySchedule(password, nBits);

    var blockCount = Math.ceil(pl / blockSize);

    //var ciphertxt = new Array(blockCount); // ciphertext as array of strings

    for (var b = 0; b < blockCount; b++) {
        // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
        // done in two stages for 32-bit ops: using two words allows us to go past 2^32 blocks (68GB)
        for (var c = 0; c < 4; c++) counterBlock[15 - c] = (b >>> c * 8) & 0xff;
        for (var c = 0; c < 4; c++) counterBlock[15 - c - 4] = (b / 0x100000000 >>> c * 8)

        var cipherCntr = Aes.cipher(counterBlock, keySchedule); // -- encrypt counter block --

        // block size is reduced on final block
        var blockLength = b < blockCount - 1 ? blockSize : (plaintext.length - 1) % blockSize + 1;
        //var cipherChar = new Array(blockLength);

        for (var i = 0; i < blockLength; i++, ti++) { // -- xor plaintext with ciphered counter char-by-char -
            ciphertxt[ti] = fromCharCode(cipherCntr[i] ^ charCodeAt(b * blockSize + i));
        }
    }

    // Array.join is more efficient than repeated string concatenation in IE
    var ciphertext = !to ? Base64.encode(ciphertxt.join('')) : ciphertxt

    //alert((new Date()) - t);
    return ciphertext;
}

/** 
 * Decrypt a text encrypted by AES in counter mode of operation
 *
 * @param {String} ciphertext Source text to be encrypted
 * @param {String} password   The password to use to generate a key
 * @param {Number} nBits      Number of bits to be used in the key (128, 192, or 256)
 * @returns {String}          Decrypted text
 */
Aes.Ctr.decrypt = function(ciphertext, password, nBits, to) {
    var blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
    if (!(nBits == 128 || nBits == 192 || nBits == 256)) return ''; // standard allows 128/192/256 bit keys
    var st = typeof(ciphertext) == "string"
    ciphertext = st ? Base64.decode(ciphertext) : ciphertext;
    //var t = new Date();  // timer

    var charCodeAt = st ? function(id) { return ciphertext.charCodeAt(id) } : function(id) { return ciphertext[id] }
    var fromCharCode = !to ? function(id) { return String.fromCharCode(id) } : function(id) { return id }

    // recover nonce from 1st 8 bytes of ciphertext
    var counterBlock = new Array(8);
    for (var i = 0; i < 8; i++) counterBlock[i] = charCodeAt(i);

    // generate key schedule
    var keySchedule = this.getKeySchedule(password, nBits);

    // ciphertext is now array of block-length strings
    var cl = ciphertext.length || ciphertext.byteLength || 0
    var plaintxt = (!to || to == 1) ? new Array(cl - 8) : new Uint8Array(cl - 8)

    // separate ciphertext into blocks (skipping past initial 8 bytes)
    var nBlocks = Math.ceil((cl - 8) / blockSize);
    var ct = new Array(nBlocks);
    for (var b = 0; b < nBlocks - 1; b++) {
        ct[b] = blockSize
    };
    ct[b] = (cl - 8) - b * blockSize

    // plaintext will get generated block-by-block into array of block-length strings 
    for (var b = 0, ti = 0, ti2 = 8; b < nBlocks; b++) {
        // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
        for (var c = 0; c < 4; c++) counterBlock[15 - c] = ((b) >>> c * 8) & 0xff;
        for (var c = 0; c < 4; c++) counterBlock[15 - c - 4] = (((b + 1) / 0x100000000 - 1) >>> c * 8) & 0xff;

        var cipherCntr = Aes.cipher(counterBlock, keySchedule); // encrypt counter block 
        for (var i = 0; i < ct[b]; i++, ti++, ti2++) {
            // -- xor plaintxt with ciphered counter byte-by-byte -- 
            plaintxt[ti] = fromCharCode(cipherCntr[i] ^ charCodeAt(ti2));
        }
    }
    // join array of blocks into single plaintext string
    var plaintext = !to ? Utf8.decode(plaintxt.join('')) : plaintxt; // decode from UTF8 back to Unicode multi-byte chars

    //alert((new Date()) - t);
    return plaintext;
}






/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  Base64 class: Base 64 encoding / decoding (c) Chris Veness 2002-2012                          */
/*    note: depends on Utf8 class                                                                 */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

var Base64 = {}; // Base64 namespace

Base64.code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

/**
 * Encode string into Base64, as defined by RFC 4648 [http://tools.ietf.org/html/rfc4648]
 * (instance method extending String object). As per RFC 4648, no newlines are added.
 *
 * @param {String} str The string to be encoded as base-64
 * @param {Boolean} [utf8encode=false] Flag to indicate whether str is Unicode string to be encoded 
 *   to UTF8 before conversion to base64; otherwise string is assumed to be 8-bit characters
 * @returns {String} Base64-encoded string
 */
Base64.encode = function(str, utf8encode) { // http://tools.ietf.org/html/rfc4648
    utf8encode = (typeof utf8encode == 'undefined') ? false : utf8encode;
    var o1, o2, o3, bits, h1, h2, h3, h4, e = [],
        pad = '',
        c, plain, coded;
    var b64 = Base64.code;

    plain = utf8encode ? str.encodeUTF8() : str;

    c = plain.length % 3; // pad string to length of multiple of 3
    if (c > 0) {
        while (c++ < 3) {
            pad += '=';
            plain += '\0';
        }
    }
    // note: doing padding here saves us doing special-case packing for trailing 1 or 2 chars

    for (c = 0; c < plain.length; c += 3) { // pack three octets into four hexets
        o1 = plain.charCodeAt(c);
        o2 = plain.charCodeAt(c + 1);
        o3 = plain.charCodeAt(c + 2);

        bits = o1 << 16 | o2 << 8 | o3;

        h1 = bits >> 18 & 0x3f;
        h2 = bits >> 12 & 0x3f;
        h3 = bits >> 6 & 0x3f;
        h4 = bits & 0x3f;

        // use hextets to index into code string
        e[c / 3] = b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);
    }
    coded = e.join(''); // join() is far faster than repeated string concatenation in IE

    // replace 'A's from padded nulls with '='s
    coded = coded.slice(0, coded.length - pad.length) + pad;

    return coded;
}

/**
 * Decode string from Base64, as defined by RFC 4648 [http://tools.ietf.org/html/rfc4648]
 * (instance method extending String object). As per RFC 4648, newlines are not catered for.
 *
 * @param {String} str The string to be decoded from base-64
 * @param {Boolean} [utf8decode=false] Flag to indicate whether str is Unicode string to be decoded 
 *   from UTF8 after conversion from base64
 * @returns {String} decoded string
 */
Base64.decode = function(str, utf8decode) {
    utf8decode = (typeof utf8decode == 'undefined') ? false : utf8decode;
    var o1, o2, o3, h1, h2, h3, h4, bits, d = [],
        plain, coded;
    var b64 = Base64.code;

    coded = utf8decode ? str.decodeUTF8() : str;


    for (var c = 0; c < coded.length; c += 4) { // unpack four hexets into three octets
        h1 = b64.indexOf(coded.charAt(c));
        h2 = b64.indexOf(coded.charAt(c + 1));
        h3 = b64.indexOf(coded.charAt(c + 2));
        h4 = b64.indexOf(coded.charAt(c + 3));

        bits = h1 << 18 | h2 << 12 | h3 << 6 | h4;

        o1 = bits >>> 16 & 0xff;
        o2 = bits >>> 8 & 0xff;
        o3 = bits & 0xff;

        d[c / 4] = String.fromCharCode(o1, o2, o3);
        // check for padding
        if (h4 == 0x40) d[c / 4] = String.fromCharCode(o1, o2);
        if (h3 == 0x40) d[c / 4] = String.fromCharCode(o1);
    }
    plain = d.join(''); // join() is far faster than repeated string concatenation in IE

    return utf8decode ? plain.decodeUTF8() : plain;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  Utf8 class: encode / decode between multi-byte Unicode characters and UTF-8 multiple          */
/*              single-byte character encoding (c) Chris Veness 2002-2012                         */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

var Utf8 = {}; // Utf8 namespace

/**
 * Encode multi-byte Unicode string into utf-8 multiple single-byte characters 
 * (BMP / basic multilingual plane only)
 *
 * Chars in range U+0080 - U+07FF are encoded in 2 chars, U+0800 - U+FFFF in 3 chars
 *
 * @param {String} strUni Unicode string to be encoded as UTF-8
 * @returns {String} encoded string
 */
Utf8.encode = function(strUni) {
    // use regular expressions & String.replace callback function for better efficiency 
    // than procedural approaches
    var strUtf = strUni.replace(
        /[\u0080-\u07ff]/g, // U+0080 - U+07FF => 2 bytes 110yyyyy, 10zzzzzz
        function(c) {
            var cc = c.charCodeAt(0);
            return String.fromCharCode(0xc0 | cc >> 6, 0x80 | cc & 0x3f);
        }
    );
    strUtf = strUtf.replace(
        /[\u0800-\uffff]/g, // U+0800 - U+FFFF => 3 bytes 1110xxxx, 10yyyyyy, 10zzzzzz
        function(c) {
            var cc = c.charCodeAt(0);
            return String.fromCharCode(0xe0 | cc >> 12, 0x80 | cc >> 6 & 0x3F, 0x80 | cc & 0x3f);
        }
    );
    return strUtf;
}

/**
 * Decode utf-8 encoded string back into multi-byte Unicode characters
 *
 * @param {String} strUtf UTF-8 string to be decoded back to Unicode
 * @returns {String} decoded string
 */
Utf8.decode = function(strUtf) {
    // note: decode 3-byte chars first as decoded 2-byte strings could appear to be 3-byte char!
    var strUni = strUtf.replace(
        /[\u00e0-\u00ef][\u0080-\u00bf][\u0080-\u00bf]/g, // 3-byte chars
        function(c) { // (note parentheses for precence)
            var cc = ((c.charCodeAt(0) & 0x0f) << 12) | ((c.charCodeAt(1) & 0x3f) << 6) | (c.charCodeAt(2) & 0x3f);
            return String.fromCharCode(cc);
        }
    );
    strUni = strUni.replace(
        /[\u00c0-\u00df][\u0080-\u00bf]/g, // 2-byte chars
        function(c) { // (note parentheses for precence)
            var cc = (c.charCodeAt(0) & 0x1f) << 6 | c.charCodeAt(1) & 0x3f;
            return String.fromCharCode(cc);
        }
    );
    return strUni;
}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */